When you search for a company in maps, you can hover your mouse over the map and see additional text.

This looks like it comes from the website of the company, from the metadescription, or body if no metadescription exists.

Example:

See "Welcome to FMD..." below the marker.

The description of this site in Google's index no longer reflects the short text below, so perhaps it comes from somewhere else? Note that this it is not in Places directly, it got here through Google's indexing process.